Chapter 10

Chapter 10 - Canard

This chapter opens up a new dimension so to speak, as I will start shaping foam in 3-dimensions. I have to hotwire Styrofoam to make the airfoil for the canard.
It's not possible to get the right type of Styrofoam in Norway - I can import it from USA but since the shipping is very expensive I found a company in Germany where I bought all the Styrofoam I need for both the canard and the wings.

2012-03-10: Then I carefully cut them out using the plans method. I cut them oversized and thereafter sanded them smooth and accurate using various sanding-tools from a belt-sander to a Dremel. Then I stacked them ontop of eachother using the WL as a common reference and drilled three holes in them. I will use drywall-screws to fasten the templates to the foam instead of nails. Drywall-screws fasten the templates tighter than nails. It's very important to get the templates as smooth as possible to avoid the hotwire-thread to snag.

2012-03-10: My hotwire-setup is identical to the plans setup. I use 2 12V car-batteries connected in series and a zig-zag resistor-plate to adjust the current and heat. The saw is made of a 1.5" x 3" piece of wood, 180cm long. It has two positions, full length and a shorter length (90 cm). Makes it easier to cut smaller parts with a not so long wire.

2012-03-17: My wife helped me with the hot-wiring of the canard-cores. It was kinda fun and turned out pretty ok. Not perfect, but good enough to work with. On the picture all the elements of the canard and the foam for the elevators are laid out on the work-bench. Total length is 358 cm.

2012-04-02: Before cutting off the leading edge of the cores, I need to drill some holes in the foam-cores and place wooden dowels through the aft and the front part of the core. This is done to ensure that when I glue the leading edge back on, the dowels will act as a guide to get the cores aligned properly. The plan calls out for 1/4" dowels. I happened to have some thinner wooden sticks we use to make BBQ-skewers of. These was perfect for the job. I put one stick in the drill and made perfect holes for the other sticks.

2012-04-02: The last step in Step 1 is to cut off the leading edge of the center-core and the two inner-cores. Important note is to mark the cores properly so it's easy to attach them correctly back on.

2012-04-04: I bought the lift-tabs and inserts from CG Products (Cozy Girrrls). To align the cores I used two aluminum straightedges leveled off in all ways. Bondoed the straightedges to the working-table, then I glued the cores together and bondoed the foam-cores to the straightedges. I used a laser to align the shearweb-face of each core. I also used a string over the centerline to ensure that the height of all the cores is equal over the whole span.
I discovered that the cores must have had some internal tension, as they all are somewhat warped. I will correct this when they are cured by shimming them sideways to ensure that they are straight all over when I start with the shear-web.

2012-04-06: I recessed the foam where the inserts for the lift-tabs are placed. I followed the plans and used some scrap metal and bolted the inserts to this. Had to use some random bolts as you can see... :-) Used dry micro under the inserts and let the whole thing cure. Meanwhile I cut the glass for the shear-web.

2012-04-08: After cutting all the glass to the shear-web I started to think, and came to the conclusion that it must be easier to lay up all the glass on plastic, trim it and then lay it onto the foam directly in one piece, instead of laying up the layers one after one on the foam. Doing it this way makes it easier to handle the loose strands of glass from the UNI.
I layed a long piece of paper on the table and marked all the edges for the various layers of the glass. I then covered it with saran-wrap, glassed all the UNI plus the long BID-ply. Then I covered it all with a new layer of saran-wrap and trimmed the edges.
At last I managed to move all the glass in one piece onto the micro-slurried foam and made it lay down very nicely. If I have to make another canard, I would definitely do it the same way again.

2012-04-08: When the shear-web glass was layed down and squeeged, I glassed the 9 small bid-pieces over the aluminium-inserts and covered it with a larger ply of BID, then peel-plied everything and set to cure.

2012-04-15: The lift-tabs are in place, fastened with three bolts as per plan. This will be the last time I touch these as they will be buried inside the canard for the rest of the lifetime hopefully.

2012-05-1: This step started with making 10 jigs according to the plans (K-jigs). Made them of 12mm particle-board. Instead of using the table directly I used the two straightedges and leveled them off in both directions. Then I bondoed the straightedge to the table, and the jigs to the straightedge. Makes a firm platform for the canard later.

2012-05-6: I started to adjust the front part of the canard-cores to the aft-part / shear-web. Since the shear-web is thicker on the middle I had to remove some of the foam from the front cores to get a straight leading edge. I also had to remove some foam where the lift-tabs meet the front core. Then I fastened the aft part of the canard-sections with double-sided carpet-tape to the jigs instead of the 5min-epoxy. I microed the front part to the shear-web as well as the outer-cores to the rest of the canard. I used duct-tape to fasten the front-part to the aft part and weighed the whole construction thoroughly down.

2012-05-19: I made some simple tools in preparation for this step. The template is to be used to see when the spar-cap is filled. Then I made a 3" wide squeege of an old credit-card, as well as a comb to use on the fiber-strands of the UNI to make them as straight as possible. I didn't use the template since the masking (see the next picture) made it impossible. Instead I used a straight stick and checked when the cap was level with the foam by just holding it across the spar as I filled it up.

2012-05-19: After filling the cap completly I removed the masking, cleaned up some epoxy-spill on the foam, peel-plied everything and let the spar cap cure.

It said in the plans that this step should take 2-3 hours. I used 6 hours!

Step 5:Applying the bottom skin